This invention relates to an operating mechanism of an electric machine, apparatus, device or component part thereof, hereinafter merely called an electric device for brevity.
A rotary electric device, for example a variable resistor and a rotary switch, utilized in a stereo-amplifier and in many other apparatus has been mounted directly on a front panel of a casing or on a chassis disposed near the front panel, and operated by a handle or knob on the front side of the panel. In most cases such rotary electric device is disposed to ensure electrical connection between other electric component parts mounted on a printed circuit board or between such other component parts and pin jacks terminals, etc. which are mounted on a rear panel. In such a case, as the distance between the rotary electric device and the other component parts is large, relatively long wiring conductors must be used. Such long wiring is not efficient and requires a large amount of material thus increasing the cost of manufacturing. In an electric device processing a very small signal, a long wiring conductor also causes noise by electromagnetic induction and increases stray capacitance thereby degrading the signal to noise ratio and frequency characteristic. Moreover long wiring conductors render it difficult to neatly arrange the component parts of the device.
To solve this problem I previously invented an operating mechanism of an electric device wherein component parts such as a rotary rheostat and a rotary switch are disposed in the rear portion inside of the electric device and these component parts are operated by relatively long shafts connected therewith through disengageable and foldable couplings and provided with knobs on the front side of the panel so as to make as short as possible the wiring conductors and making easy removal and mounting of the component parts. (Japanese utility model application No. 89929 of 1975)
With this construction, however, it is necessary to arrange the knobs and the associated component parts on respective straight lines. Because, if the knob is mounted on an axis eccentric with respect to the axis of the operating shaft a stress corresponding to the eccentricity would be applied to the component part thus decreasing the accuracy and life thereof as well as the operation feeling.
Such straight arrangement decreases the versatility in the layout of the component parts in the electric device. Moreover, the positions of the knobs are limited by the positions of such rotary component parts as variable resistors and switches. This decreases the freedom of the ornamental design of the front panel.